I currently work from home and was thinking i'd like to try to do that in France perhaps in the Loire region. What would the tax implications/ legalities be regarding this. I am fully employed under PAYE currently.
As an EU citizen, there is no legal implication for doing what you do now in France, provided it isn't illegal (e.g. spamming, hacking, espionage etc) and you won't become a burden on the state (i.e. having a minimum income, set by each EU state).
If you are moving permanently to France, and spending more than half a year there, the Frech may classify you as a resident and will try to tax you on your worlwide income. But as there is a double taxation relief between the two countries, you won't be taxed twice, but you still have to make your tax return in both countries. What normally happens is that if there is a French tax liability, any tax you've paid in UK can be set against it, paying only the balance. You may need the service of a good international accountant well versed in tax rules in both countries. Or read a book on it plus online help. But you need to have a good grasp of French. Different tax years (in France it's calendar year, Jan-Dec, not April 6-April 5) can catch you out, so beware.
As for sociial security deductions, if you continue to pay NI contributions in UK, you should get EHIC and ask your employer to apply for E101 (up to a year). Longer than a year, you will need E106. You and your family will be able to access French health care system on the same basis as locals. You will continue to accrue credits for UK state pension as long as you keep paying NI contributions.
Technically if you're in France for more than six months a year, then your tax liability will be in France. Once you have made the permanent move, you no longer have to make a declaration in the UK on the income you derive from your employment. But you do have to set up the appropriate business entity in France in order to operate within the rules. The half year + residence rule is key.
Setting up a small business in France is by no means simple. I'm out of touch as far as current tax/NI levels in the UK are concerned, but they are prohibitively high in France in some cases for small businesses, even if the Sarko administration has come up with some slightly less onerous set-ups.
Edit - the logic is pretty clear - if you benefit from public services in France (by being permanently resident there) then you should contribute towards their maintenance and costs.